- Preheat oven to 350°F. Stir flour, baking powder, ginger, baking soda and cinnamon in medium bowl.
- Beat butter, sugar and molasses in large bowl. Mix in egg. Add flour mixture alternately with water, stirring just until blended. Pour into greased 9-inch square baking pan.
- Bake 40 minutes. Cool in pan on wire rack 10 minutes. Invert cake onto wire rack to cool completely. Serve with whipped cream, if desired.